Re: [Amel Yacht Owners] Re: Shore Power Configuration
Andrew & Kate Lamb
We have a total run of somewhere between 15-20 meters (internal cabling + shore power cable) of twin and earth 4mm2 cross section double insulated cable from the shore power to the 32A circuit breaker in the engine room, then onto the 7.5KW rated isolation transformer. All the online and offline calculators/calculations that I have done seem to suggest that this is adequate.
Canet en Roussillion, France
From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Wednesday, November 18, 2015 3:23 PM
Subject: Re: [Amel Yacht Owners] Re: Shore Power Configuration
Bill, thanks for the feedback. Trust me, I am not trying to question what Amel did, as I am sure they have been installing safe and effective electrical systems in their boats. And I also agree that I do not want to "de-Amel" my boat. I like it essentially the way it is.
But I do have some concerns that my Amel 54 may not be configured as Amel intended, and what I have is definitely not safe. I was hoping to see what others have in their shore power systems to see if I have the right setup. Right now I have a single 32A/230V Hubbel shore power inlet coupled to a 32A/230V circuit breaker in the lazarette feeding my shore power line to the automatic transfer switch in the engine room. The Amel electrical schematics I have indicate there should be a 16A/230V breaker for the 50Hz feeder and also a 32A breaker for a 120V/60Hz feeder with a step-up transformer. I do not have the 16A breaker or the transformer. I am concerned about the possibility that someone may connect my shore power inlet to a 230V or 240V connection (which is what you have to do of course whether in Europe or the US) but then try to run everything in the boat. That would overload my 4mm2 wiring.
I certainly am not immune to making mistakes, but I do think I am looking at this correctly. I am an electrical engineer, so right or wrong I have based my shore power assessments on US National Electrical Code rules. Your approach to determining wire size based on voltage and voltage drop also can be used, but is only really appropriate for DC wiring and not higher voltage AC systems (whether they are 120V or 230V), where voltage drop is not a concern in a house or boat. Voltage drop is only important if you are looking at DC circuits (where we are dealing with 12 or 24 volts).
Respectfully, I must also point out a few issues with your numbers. 4mm2, commonly available in Europe, is a cross-sectional measurement of the wire and not the diameter or circumference. It is the equivalent of a US Wire Gauge Size 11 per the conversion tables. I can see how you might have equated it to a 6 AWG. Since 11 gauge wire is not commonly available in the US, you would have to use 12 gauge wire to be safe.
Current through the wire is the issue and not voltage or frequency. 12 gauge wire (or 4mm2) on any AC circuit (less than 600 volts) is good for up to a 20A breaker and a maximum of 16 amps of continuous current at either 120V or 230V. If you connect a European 230V (or US 240V) power source to a 32A breaker (as I have), the breaker would allow a huge current (up to about 30 amps before tripping) to pass through my 4mm2 wire. In order to handle that much current, I would need to replace the wiring with 6mm2 wire (or 10 AWG in the US). i do not want to do that, as I agree with you that Amel clearly planned for 4mm2 wiring on the 230V/50Hz shore power feeder, and hence the rationale for a 16A circuit breaker. Also I think you are correct that the vast majority of power systems available throughout Europe are indeed 16A rather than 32A.
Those are the reasons why I think the circuit breaker I have is wrong and I should degrade it to 16 amps at 230V. Of course, that would limit my power capacity, but I think that is what Amel would have installed. What size shore power connector and circuit breaker do you have?
s/v Phantom Amel 54
On Wednesday, November 18, 2015 3:59 AM, "'Bill & Judy Rouse' yahoogroups@... [amelyachtowners]" <amelyachtowners@...> wrote:
I think that you are incorrect on required wire size. How did you calculate that it is wrong? Based on: Wire Circular mils =2 x ρ x I x L / (%Allowable Voltage drop of source voltage)
4mm = 6 gauge...and 6 gauge is adequate for 230VAC 50htz for 200+ foot length at 3%Allowable Voltage drop.
Is it possible that you have made a mistake? Or, is it possible that your calculations of wire size are based on 110VAC common to the USA?
A word of advice to you. The last person you should doubt in terms of Amel systems design is Amel. And the last thing that you want to do with an Amel is to Un-Amel your Amel.
Also, I sent you a private message.
On Tue, Nov 17, 2015 at 4:24 PM, James Wendell ms42phantom54@... [amelyachtowners] <amelyachtowners@...> wrote: